Chat show host David Letterman made an startling on air revelation on Thursday when he admitted he was the victim of a $2 million extortion attempt and that he had slept with female members of his staff.

The TV personality revealed that three weeks ago he had discovered a package in his car containing proof of "the terrible things I have done".

It was left by "a guy" who threatened to write a book and screenplay about the broadcaster if he wasn't paid money.

David decided to take action and told his audience that on that very morning he had testified before a grand jury after participating in a sting operation involving a fake cheque.

Speaking of his testimony, David said: "I had to tell them all of the creepy things that I have done…The creepy stuff was that I have had sex with women who work for me on this show."

"I feel like I need to protect these people. I need to certainly protect my family," he added.

The alleged extortionist – revealed in a statement by CBS to be a producer on US TV show 48 Hours – has been arrested.

David concluded that he had nothing further say at this time and that he hoped he would be able to protect his job.

The 62-year-old broadcaster and his long-term girlfriend Regina Lasko married in March and they have a six-year-old son Harry.